This invention relates to wall mounted electronic thermostats and, in particular, to power supplies for such thermostats.
Wall mounted electronic thermostats for controlling temperatures in rooms are well known. These devices are commonly powered by batteries or by low voltage alternating current sources, typically 24 volts AC. The 24 volt AC power must be reduced to a lower level DC voltage for use in supplying power to the various component parts of the thermostat. This has heretofore been accomplished by various power supply circuits, which employ resistors to reduce the voltage level. These voltage dropping resistors dissipate heat which in turn can impact the sensing of room temperature by the thermostat. These resistors also produce additional loads on the transformer, which provides the stepped down 24 volts AC to the thermostat.